The present invention relates to a stereoscopic display method, a forming method, and a stereoscopic display apparatus of a hologram for performing a stereoscopic display by forming a hologram of a virtual object or an object which actually exists and, more particularly, to a stereoscopic display method, a forming method, and a stereoscopic display apparatus of a hologram for performing a natural stereoscopic display by using a 2-dimensional image.
A stereoscopic display is a display for enabling a depth or a thickness of a 3-dimensional object to be easily visually understood. Such a stereoscopic display is strongly demanded in a display of a structural object designed by a CAD or the like, a display of a medical image, or the like. On the other hand, a solid image is more impressive as compared with a 2-dimensional display and is also used in a display for amusement in an amusement park, a movie, or the like.
Hitherto, with respect to the stereoscopic display, various kinds of methods have already been proposed. There is a hologram as means in which an observer can see a solid image without using special glasses. The hologram is a special image in which an object image was recorded by using an interference operation of the light. With regard to a still object, a color hologram having a depth feeling has already been produced. On the other hand, as a method whereby a virtual object having a 3-dimensional structure formed by the CAD or the like is stereoscopically seen, there is a computer graphics (CG). The computer graphics is a technique in which a 2-dimensional image, when an object is seen from a predetermined direction, is calculated and is really expressed in consideration of the reflection or shadow of the light. Since the computer graphics, however, intends to obtain a 2-dimensional image, a stereoscopic feeling is insufficient. It is possible to display, with a stereoscopic feeling, by a holographic stereogram system such that 2-dimensional images, when an object is seen from various directions, are sequentially recorded into stripe-like regions each having a microwidth in the horizontal direction and a width of screen in the vertical direction, by the holographic exposure on the basis of the 2-dimensional image by the computer graphics.
According to the conventional holographic stereogram, however, a 2-dimensional image is fundamentally seen and the surface at which a focal point of the eyes is located doesn't coincide with the position of the image which is observed by a parallax of both eyes. Therefore, it is hard to see and such a state results in a cause of a fatigue. Particularly, in a case of displaying an image of a deep depth, a burden on the eyes increases and such a stereoscopic display is unpreferable. The conventional hologram is recorded onto a film-like medium and it takes a time to develop the image, so that it is inconvenient as a stereoscopic display system. Further, the display contents cannot be rewritten.